Abstract: Objective · To evaluate the efficacy and safety of prophylactic phenylephrine in parturients prone to develop spinal hypotension.  Methods · Fifty parturients undergoing elective cesarean delivery whose preoperative positional mean arterial pressure (MAP) change from supine to right lateral position were bigger than 8 mmHg (1 mmHg=0.133 kPa) were randomly allocated into 2 groups, i.e. high-risk prevented group (group A) and high-risk control group (group B). Another 25 parturients whose positional MAP change were smaller than 8 mmHg were allocated into low-risk prevented group (group C). After spinal anesthesia, phenylephrine (50 µg bolus and 50 µg/min infusion) was given immediately to group A and C, and the pump speed was adjusted to 25 µg/min 10 min later till fetuses were removed. Normal saline with the  same volume and pump speed was given to group B. The incidences of hypotension, reactive hypertension, and bradycardia, the occurrence of nausea and vomiting, and Apgar scores at 1 min and 5 min of three groups were compared.  Results · The incidence of hypotension in group A was 28%, 76% in group B, and 16% in group C. Group A and C were significantly lower than group B (P<0.01). The reactive hypertension rate was 4% in group A and 28% in group C. There was a difference between these two group (P=0.015). There were no significant differences among 3 groups in Apgar scores at 1 min and 5 min (P>0.05).  Conclusion · Prophylactic phenylephrine in the paturients prone to develop spinal hypotension reduces the incidence of spinal hypotension without obvious adverse effects on the paturients and neonates.

Key words:  cesarean delivery, spinal-epidural combination anesthesia, spinal hypotension, reactive hypertension, phenylephrine